On August 13, 1868 a great earthquake in the offshore area near Arica, Peru (at that time) generated a Pacific-wide tsunami. Locally, the disaster caused extensive damage to villages and towns alog the coast of Southern Peru and Northern Chile and killed hundreds of people in the immediate region. Tsunami waves caused extensive destruction to coastal towns and ports along the coast of Peru and Northern Chile. Iquique, Mejillones, Tocopilla, Coquimbo, Constitución, Tomé, Concepción, Talcahuano, Coronel and other towns and villages were particularly damaged. The historical records and literature pertaining to this event were thoroughly examined by Iida, Cox and Pararas-Carayannis in their catalog of Tsunamis in the Pacific (1967) in an effort to reconcile differerences in reported dates, tsunami travel and heights and events related to the near and far-field effects of the tsunami.

THE EARTHQUAKE

Date and Origin Time - About 17:15 (local time) on Aufust 13, 1868.

Magnitude - 8.5 Richter scale (Reconstructed estimate)

Epicenter - 18.05 South, 71.? West at sea about 70 km from Arica.

Focal depth - Shallow

Aftershocks - There were no instrumental recordings at that time but it was reported that several strong aftershocks occurred in the following hours, days, weeks and months.

Ground Motions - According to eyewitness reports the ground motions lasted four to five minutes. However, this seems rather long, so there is a possibility that the reports did not distinguish between the main shock and the stong aftershcoks that followed.

Death Toll and Damages - The historical accounts of the death toll from this event differ significantly. According to Milne (1915) the tsunami caused 25,000 deaths. It is not clear how he arrived at this estimate. Locally, there was extensive loss of life and destruction in the upper part of the city (Arica) from the earthquake. There was extensive destruction by the tsunami of the lower part of the city. It is estimated that between 300 to 350 people lost their lives in Arica - a city with city population of 10,000 at the time.

THE TSUNAMI

Bothe Near and Far-field effects of the1868 tsunami are summarized in the Table at another section. Height are based on either instrumental recordings by tide stations or on visual observations of runup measurements.

There was severe damage at Arica. The first sea level fluctuation was a withdrawal of the sea 22 minutes after the earthquake. Ships in the harbor sat on the bottom. Two subsequent waves crushed on the port's wharf - the first sweeping the people who were providing aid to the crew of beached ships. These two waves had an estimated runup of 10 meters. Approximately two hours later, at 19:10 (local time), two more waves appeared like water walls of about 14 meters in height and struck violently the coastal area of Arica, spreading widespread destruction up to the elevation where the First Church of Arica (later renamed Church of San Marcos) was located. The reports on maximum tsunami wave height differ. Montessus de Ballore (1907) refers to a report by Schmick (1879) of a 21 m. runup at San Pedro. Gutenberg andRichter (1959) give the reported height as 18 m. and indicate it is most probably a mistake. However, the 14 m maximum wave at Arica is well documented. Oscillations in the harbor continued for three days.

Artistic Rendering of the 1868 Tsunami in Arica (then city of Peru)

IMPACT OF TSUNAMI ON SHIPS IN ARICA

There were several ships anchored offshore near Arica at the time. Two were US Navy ships - the USS Fredonia and the USS Wateree. These two ships had moved to Arica from Callao, Peru, because, at the time, there were reported cases of yellow fever. When the tsunami occurred and the water first withdrew, the USS Fredonia sat on the bottom. Maximum wave, 2 hr after the quake, wrecked most ships in harbor. The wave completely demolished the Fredonia and drowned twenty-seven of its officers and men. Only three of the officers - who were on shore - survived and only two of the total crew were rescued from the sea. Two other ships, the Peruvian corvette America and the English bark Chanarcillo were also destroyed and many of their sailors drowned. The boats were carried about 300 m. inland.

In terms of lives lost by the impact of the 1868 tsunami, the USS “Wateree” fared much better. The ship's design of a flat bottom, with wheels on both sides and double rudders in the bow and stern, gave the ship stability which prevented its breaching - thus saving the crew from harm. However, the ship was badly damaged and since it was beyond any cost of effective repair, it was sold for its scrap value. All of Wateree's crew survived with the exception of one seaman who was was tending the captain's gig and who was carried out to sea and drowned.

The accounts on how far the USS “Wateree” was dragged inland by the 1868 tsunami difer and are somewhat misleading or eroneous. According to one account, the USS “Wateree” was dragged about 3km inland and deposited at what is now known as "Chinchorro" beach at the foot of Cerro Chuño (a coastal hill). However, another account states that a subsequent tsunami in 1877 refloated the ship and deposited approximately 7.4 km in a northeast direction and beached about 1850 meters away of the coastline. This account seems to be inaccurate.

There is also an account of events of that day by the captain the USS “Wateree”, U.S. Navy Commander, JAMES H. GILLIS. (See Page on the "Loss of the USS Wateree" with additional photographs of the U.S. Navy Archives). The account by Gillis states that while on the ship he felt a trembling, then heard a rumbling sound from the shore (Taylor, Washington Times). Looking toward the town of Arica, he saw buildings collapsing and realized that the town was impacted by a severe earthquake. Immediately, he ordered the deployment of a second anchor for the ship, then called for his gig and accompanied by the ship's doctor, set out to render assistance.

According to his account, when they reached shore, the water in the harbor was receding rapidly and various small crafs were carried around by stong currents. Shortly afterwards the first tsunami wave arrived and the smaller boats begun to smash against the shore. This first wave rose the USS “Wateree” on its crest. Already, most of the town of Arica lay in ruins and its harbor was filled with debris, lumber, shrubbery, cattle and even railroad cars. The cries of the injured could be heard occasionally over the sound of the wave. After the first wave receded, a second wave arrived. Thee USS Wateree had already paid out nearly 600 feet on each of its two anchor chains, which held. The larger ships in the harbor, including Wateree and Fredonia, appeared to be holding their own. However, around 6:30 that evening, a much larger wave with an estimated crest at more than 40 feet crashed onto the deck of the Wateree and swung violently on its anchors

Gillis reported that the ship begunto drift rapidly seaward, when another wave arrived and swung the vessel violently around. At that time the severe strain on the chains resulted in the break of the starboard chain and the ship begun drifting rapidly towards shore. Subsequently, the Wateree was thrown on its side and continued to be impacted by surging sea. When Gillis returned, the Wateree was resting on a point nearly 500 yards from the high-water mark, some 12 feet above sea level. Fortunately there was only one serious injury of the crew. However, the tsunami wrecked completed the USS Fredonia and 27 members of its crew lost their lives.

US Navy Photograph of the beached boats USS “Wateree” and of the Peruvian corvette “America” in the background (Halftone image, copied from the U.S. Naval Institute "Proceedings", July 1926, page 1323)

FAR-FIELD EFFECTS - There are several errors in the literature regarding the dates of the tsunami . For example, Alexander (1893) gives the date of impact in the Hawaiian islands as August 15, 1868 while other Hawaiian publications erroneously report the year of occurrence as 1871. Richter shows it as occurring on August 8, while Milne (1908) gives a date of August. 11, and Iida as August. 16 (Pararas-Carayannis, 1969). Some authors show dates of August 14 and 15 but these are dates of tsunami observation at distant points, not dates of generation. For example, Alexander 91891) gives the date of the tsunami in the Hawaiian Islands as August 15, 1868 and other Hawaiian publications erroneously report the year of occurrence as 1871 (Pararas-Carayannis, 1969).

Similarly there are many errors in the literature concerning tsunami runup at distant locations. For example, Montessus de Balolore (1907) refers to a report by Schmick (1879) of a 21 m. runup at San Pedro, California. Gutenberg and Richter (1959) give the reported height as 18 m. for San Pedro and indiacate it is most probably a mistake - which it was.

Ths tsunami caused severe damage at Kahului, on the ilsnd of Maui and at Hilo, Island of Hawaii Hawaii where the maximum runup was 4.6 meters and left a mark on a coconut tree. In Kalapana plain 20 acres of land were flooded.

The table below gives a much more accurate accountof far-field tsunami runups. There were significant Pacific-wide effects from the tsunami - which was particularly damaging in New Zealand, Australia, Samoa, Hawaii, San Pedro in California and Japan.

TABLE. NEAR AND FAR-FIELD AMPLITUDES OF THE 13 AUGUST 1868 PERU/CHILE TSUNAMI

The amplitude listed is either a mesasured runup (maximum vertical elevation wave reached above sea level at the time of tsunami) or a zero-to-peak tide gage reading. Both are given in meters.

The entire west coast of South America is outlined by the eastern border of the Nazca tectonic plate and is characterized by its extreme seismicity, particularly along the zone where the Nazca tectonic plate subducts the continent. There is a very narrow seismic band (100-150 km wide) between the Andes mountain range and the Peru-Chile Trench. Major differences is seismicity, in morphology of the coast and in potential for generation of large tsunamis exist along the entire coastline of Chile. An outstanding and well-known feature of the spatial distribution of hypocenters along South America is the gap in seismic activity between depths of 320 and 525 kilometers. The deep earthquakes (deeper than 525 km) define two relatively narrow belts of activity, and the number of small-magnitude events relative to the number of large-magnitude events is very low. The intermediate-depth activity tends to cluster in space. There is a peak in activity between depths ofabout 100 and 130 km; most of these events occur between about latitudes 17ºS. and 24ºS. (near the bend in the coastline between Peru and Chile).

Chile's seismotectonic zone has three distinct segments. Each of the segments can produce earthquakes with different characteristics of focal mechanisms and crustal displacements and has the potential to generate destructive local as well as Pacific-wide tsunamis.

Seismicity of Northern Chile/ Southern Peru

Specifically, the northernmost region of Chile(between 18ºS. and 20ºS. latitude) where the 1868 tsunamisgenic earthquake occurred is a very active seismic zone. This northernmost region, sometimes called the "big bend" , has a history of destructive earthquakes and tsunamis. Besides the 1868 earthquake and tsunami other great tsunamigenic earthquakes in 1604, 1705 and 1877 destroyed Arica (located at 18.5ºS.latitude) as well as other coastal towns and and had Pacific-wide, destructive impacts.

Historical Tsunamis in Chile

The historic record documents that Chile is one of the most seismically active regions in the world. Since 1562 there have been at least 35 tsunamigenic earthquakes that struck its coasts, causing damage.

REFERENCES AND HISTORICAL ACCOUNTS REFERRING TO THE 1868 EARTHQUAKE AND TSUNAMI

ALEXANDER, W. D., 1891. A Brief History of the Hawaiian People, American Book Co., New York, p. 230.

HOCHSTETTER, von, F., 1868. On the earthquake in Peru on 13 August 1868 and the flood wave caused by it in the Pacific Ocean, particularly on the coasts of Chile and New Zealand [German], Sitzungeber d. k. Akad. d. Wissensch., Vienna, v. 58, no. 4, p. 837 [Not seen cited by Montessus de Ballore, 1907 and others].

HOCHSTETTER, von, F., 1869. The earthquake flood in the Pacific Ocean from 13 to 16 August 1868 and the average depths of this ocean [German], Sitzungeber d. k. Akad. d. Wissensch., Vienna,v. 59, p. 109 [Not seen, cited by Montessus de Ballore, 1907 and others].

KAWASUMI. H.. [ed.J, 1963. List of great earthquakes in and near Japan; list of great earthquakes in China; and list of great earthquakes of the world [Japanese], Ghigaku [Earth Sciences] in Rika-Nempyo [Nat. Sci. Almanac, Haruzen, Tokyo. p. 154-225.